yum groupinstall groupupgrade

[Harry Putnam]

How do the yum options groupinstall groupupgrade work?

The yum man page doesn't bother to explain any more than:
        * groupinstall [...]
        * groupupdate [...]

Which appears it would be 
 `yum groupupgrade pkg pkg2 pkg3'

That fails though so it must mean something different.
    yum groupupdate cdda2wav cdrecord
  Gathering header information file(s) from server(s)
  Server: My fedraw mirror, or real carroll rawhide, or kernel.org mirror rawhide
 Finding updated packages
 Downloading needed headers
 Getting groups from servers
 yumgroups.xml 0% |   |    0 B --:-- ET
 yumgroups.xml 100% |=========================| 411 kB    00:00